1. Field of the Invention
This invention relates to a copying apparatus for copying both sheet originals and thicker originals, and more particularly to an epoch-making copying apparatus which is capable of high-speed copy production and which incorporates various novel process means.
2. Description of the Prior Art
The conventional copying machines are generally classified into two types, one of which is only able to copy sheet originals and the other is means to copy three-dimensional originals such as books and the like.
The copiers exclusively for use with sheet originals cannot copy books or other thicker originals but are meritorious in that sheet originals can be rapidly copied simply by feeding them into an inlet for insertion and that there is no return stroke for the original carriage or the optical system during the same process, thus enhancing the copying speed correspondingly or approximately twice. These copiers have further merits in the simplicity and low cost of the entire construction, and also in the readiness with which an automatic original supply means may be added if required.
The other type of copiers, i.e. those for copying books or thicker originals have a great characteristic that they can copy both sheet originals and thicker originals. however, their construction is such that any original to be copied must be flatly spread over the original carriage, and such constructions unavoidably leads to cumbersome procedures of raising the original keep cover to place each sheet original on the original carriage, closing the keep cover and depressing the copy button, as is required to copy thicker originals. Moreover, the original carriage or the optical system operatively involves its return stroke, which means a corresponding loss of time and accordingly a corresponding reduction in copying speed for the same process. Additionally, mechanisms are not only complicated and expensive but also great difficulties will be encountered in incorporating an automatic original supply means.
For these reasons, the foregoing two conventional types of copying machines have been enjoying their unique markets, respectively.
In most offices, however, demand for copies of sheet originals is greater than that for copies of thicker originals. For this reason, those offices had to resort to copying machines for thick originals which are more expensive and less convenient to copy sheet originals.
To overcome such irrationality, there have heretofore been proposed copying apparatuses which are capable of copying thicker originals while maintaining their merits as sheet original copying apparatus. Such apparatuses are grouped into the following two types:
I. The apparatus portion overlying the path of sheet originals is detachably constructed so that when copying thicker originals, such portion may be detached from the apparatus body so as to expose the sheet original transport rolls of the apparatus body. A thicker original may be manually urged against such exposed transport rolls and transported with the aid of the rubber rolls so as to be subjected to a through-slit exposure.
II. This type is substantially identical in construction with the type I except in that there is additionally provided a carrier comprising a transparent plate of glass or plastics, on which a thicker original may be placed and transported for exposure with the edges of the carrier held by two or more pairs of transport rolls.
These two types of apparatuses are substantially similar to the sheet original copying machines in construction and accordingly in cost, but suffer from some demerits as follows:
1. From the user's point of view, removal of an apparatus portion means a considerably cumbersome procedure, and also would encounter a difficulty in providing a storage space therefor if the entire office space is limited. In case of type II, storage of the carrier would also be troublesome.
2. In case of type I, the variable manual pressure imparted to the original may cause a great variation in the load to the drive of the apparatus body. In case of type II, the thickness of the carrier may cause a corresponding variation in the length of the optical path, which in turn would result in erroneous focusing and accordingly erroneous synchronization, thus seriously affecting the quality of the resultant copies.
3. A gear sprocket wheel located at the end of original transport rolls for driving such rolls, and further in case of type II, carrier transport rolls, would project outwardly of the path for originals, thus preventing such path from being flat and accordingly preventing a portion of a bulky original from being copied.
4. Where the original to be copied has a substantial thickness like books and the leading edge of the original (as viewed in the direction of movement thereof) has a complicated configuration (due to the book cover or the opened position of the book with the page margins thereof forming a slope), the position for the leading edge of the resultant copy image may be greatly variable because the leading edge of the book or like original is detected by a detector switch designed for detecting the leading edges of sheet originals.
Thus, the copying apparatuses of the types as mentioned under items I and II above are practically unsatisfactory and even their merits are merely nominal.